[meteorite-list] OT: Listening To Fermi

From: Anita Westlake <anitawestlake_at_meteoritecentral.com>
Date: Fri, 17 Sep 2010 14:34:27 -0700 (PDT)
Message-ID: <52758.30448.qm_at_web83811.mail.sp1.yahoo.com>

Intelligent life on earth is rare too!
Anita



----- Original Message ----
From: JoshuaTreeMuseum <joshuatreemuseum at embarqmail.com>
To: meteorite-list at meteoritecentral.com
Sent: Fri, September 17, 2010 12:19:43 AM
Subject: [meteorite-list] OT: Listening To Fermi

Hi Richard;
That's an excellent argument for cancelling the silly SETI project. The key
word in your argument is "believe". You believe in the existence of exo-life
without any supporting evidence, I don't. So we can agree to disagree.

If life never existed on Mars, I can't see it existing anywhere else. But, my
beliefs are evidence based, I'll change them in a minute if someone will just
show me the money.

-----------------------------------

Phil Whitmer


-------------------------------------------------------------------------
Actually Phil, I'd disagree with that statement, even though I believe that the
universe is filled to the brim with life, I think that intelligent life is
exceedingly rare.

Personally I think that SETI is never going to find a signal, not because there
is no life out there, but that the circumstances required to find a signal is
exceedingly small. The analogy put forth by others in this thread of a child
looking out a window for 32/1000ths of a second is a good one.

Use ourselves as an example. Radio technology on earth is barely a century old
and we are already rapidly moving away from high powered transmitters to low
powered devices for communications. Our most efficient long distance
communications are already moving via fiber optics, so require no radio
transmissions whatsoever.

Ask yourself what are/or were the most powerful transmitters used?
The answer is Early Warning defense radar systems. In fact at those frequencies
Earth was brighter than the Sun. As the Cold War wound down, and the technology
improved, lower power transmitters could do the same job. For about 40 years,
Earth shined exceedingly brightly in microwaves, with a peak radiance about 1/3
through that period. So you can imagine a shell of microwaves 40 light years in
thickness traveling out from our solar system, expanding at the speed of light.
(I'm sure I'll be corrected here, but that's OK. I welcome it.)

Say a intelligent civilization, only a century behind us in technology (Almost
statistically impossible) 50 light years away from us will develop the
technology to detect radio waves of that frequency. Our microwaves from the
early warning systems have been reaching them for more than a decade already,
but they won't develop the technology to detect this radiation for another 30
years or so.

In other words, just as they gain the ability to detect our unintended signal to
them just as it has completely passed them by. Even if they point their radio
telescope directly at earth, they wouldn't hear us as our signal drops again
below the background noise.

And so it goes planet after planet as the signal extends out into space in an
ever expanding shell, growing ever weaker. If we continue our trend to become
more radio silent in other frequencies too, our civilization could become radio
dark again as far as the universe is concerned in the next hundred years or so.

Expand this problem by a more realistic estimate that civilizations become
technologically capable thousands or millions of years apart, not mere decades
apart...

Now reverse the situation. For SETI to work you have to be listening at the
precise moment the signals are passing our region of space. Miss it by a
century, a decade, a year, a day, and its too late. The signal is no longer
detectable. It may literally take many millenia before the right combination of
circumstances allow us to detect another civilization through just their radio
communications, intended or otherwise.

Ironically, I think that SETI is an experiment that should not be abandoned,
because you'll never know if there is a detectable signal if you don't look. I
just think it will never yield a positive result. However, I do believe that the
canceled Terrestrial Planet Finder mission had a much better chance to find
habitable, and planets that have abundant life.



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Received on Fri 17 Sep 2010 05:34:27 PM PDT